A water-based hybrid supercapacitor electrode material, a preparation method therefor, and an application thereof

Abstract

The application discloses a preparation method of a Ni-doped Co3O4@C aqueous system mixed type supercapacitor electrode material, which comprises the following steps: dissolving NH4Cl into ammonia, then adding finely ground CoCl2 and finely ground NiCl2 in batches, continuously stirring the solution with a glass rod during the dissolving process, and obtaining a yellow-red turbid solution; under the stirring state, adding H2O2 solution into the yellow-red turbid solution drop by drop, obtaining a purple-red solution after the dropwise adding is completed; adding concentrated hydrochloric acid into the purple-red solution drop by drop, and a purple-red precipitate is separated out after the dropwise adding is completed; adding activated carbon, heating in a steam bath for a period of time, then cooling to room temperature, performing suction filtration, drying after washing, and obtaining a dark purple solid; placing the dark purple solid into a muffle furnace to perform calcination, and obtaining black powder solid Ni-doped Co3O4@C. The cobalt complex is doped with carbon nickel to generate a novel material Ni-doped Co3O4@C with a quadrangular bipyramid structure, and the novel material is used for preparing an aqueous system mixed type supercapacitor.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of electrochemical energy storage, and particularly relates to a water-based hybrid supercapacitor electrode material and a preparation method and application thereof. BACKGROUND

[0002] The information disclosed in this Background section is only for the purpose of increasing an understanding of the general background of the application and does not necessarily constitute an admission or a recognition that the information forms part of the prior art that is already known in any country in the world.

[0003] Supercapacitors, also known as electrochemical capacitors (EC), are devices that store energy through the formation of an interfacial double-layer capacitance between the electrode and the electrolyte. They have higher specific capacitance and energy density than traditional capacitors, and higher power density and longer service life than ordinary batteries, thus having broad application prospects. However, due to the high flammability of organic solvents, commercial supercapacitors with organic electrolytes have a potential high flammability risk. Scientists have endeavored to prepare supercapacitors with aqueous electrolytes, which are non-flammable and green, and have high ion concentration and low resistance, which is conducive to improving the specific capacitance and power density of electrode materials. SUMMARY

[0004] In order to overcome the above problems, the present application provides a water-based hybrid supercapacitor electrode material and a preparation method and application thereof.

[0005] In a first aspect of the present application, a preparation method of a Ni-doped Co3O4@C water-based hybrid supercapacitor electrode material is provided, and the method comprises:

[0006] S1. Dissolve NH4Cl in ammonia water, then add finely ground CoCl2 and finely ground NiCl2 in batches, and continuously stir with a glass rod during the dissolution process to obtain a yellow-red turbid solution;

[0007] S2. Under stirring, drop H2O2 solution into the above yellow-red turbid solution drop by drop, and after the dropwise addition is completed, a purple-red solution is obtained;

[0008] S3. Under stirring, drop concentrated hydrochloric acid into the above purple-red solution drop by drop, and after the dropwise addition is completed, a purple-red precipitate is precipitated;

[0009] S4. Add activated carbon to the mixture in which the purple-red precipitate is precipitated, heat in a steam bath for a period of time, then cool to room temperature, perform suction filtration, and after washing, a deep purple solid is obtained;

[0010] S5. The deep purple solid was put into a muffle furnace for calcination to obtain black powdery solid Ni-doped Co3O4@C.

[0011] In a second aspect of the present application, a Ni-doped Co3O4@C-based aqueous hybrid supercapacitor electrode material prepared by the above preparation method is provided.

[0012] In a third aspect of the present application, the above Ni-doped Co3O4@C-based aqueous hybrid supercapacitor electrode material is applied to prepare a supercapacitor.

[0013] In a fourth aspect of the present application, a preparation method of a positive electrode sheet and a negative electrode sheet in an aqueous hybrid supercapacitor is provided, and the method comprises:

[0014] Preparation of the positive electrode sheet: Ni-doped Co3O4@C, acetylene black, polyvinylidene fluoride and N-methyl-2-pyrrolidone (NMP) are respectively poured into a mortar for grinding until a slurry is obtained without fine particles; the ground slurry is uniformly coated on the foam nickel to ensure that the upper surface of the foam nickel is completely covered by the slurry and is not transparent under sunlight; the coated foam nickel is dried to obtain a positive electrode sheet of a button-type aqueous hybrid supercapacitor.

[0015] Preparation of the negative electrode sheet: active carbon, acetylene black, polyvinylidene fluoride and N-methyl-2-pyrrolidone (NMP) are respectively poured into a mortar for grinding until a slurry is obtained without fine particles; the ground slurry is uniformly coated on the foam nickel to ensure that the upper surface of the foam nickel is completely covered by the slurry and is not transparent under sunlight; the coated foam nickel is dried to obtain a negative electrode sheet of a button-type aqueous hybrid supercapacitor.

[0016] In a fifth aspect of the present application, a positive electrode sheet and a negative electrode sheet in an aqueous hybrid supercapacitor prepared by the above preparation method are provided.

[0017] In a sixth aspect of the present application, a button-type aqueous hybrid supercapacitor is provided, which comprises a positive electrode shell, a positive electrode sheet of the above aqueous hybrid supercapacitor, a separator, a negative electrode sheet of the above aqueous hybrid supercapacitor, a negative electrode shell and an electrolyte; the electrolyte is a KOH solution.

[0018] The present application has the following advantages:

[0019] (1) The present application burns the cobalt complex doped with carbon nickel to generate a new material Ni-doped Co3O4@C with a quadrangular bipyramidal structure, which can improve the stability of the capacitor, and thus is used to prepare an aqueous hybrid supercapacitor.

[0020] (2) The buckle type aqueous hybrid supercapacitor prepared in the application has a high coulomb efficiency, and the coulomb efficiency thereof increases with the increase of the current density.

[0021] (3) The buckle type aqueous hybrid supercapacitor prepared in the application has a high area specific capacity, excellent rate performance and electrochemical cycle stability. BRIEF DESCRIPTION OF DRAWINGS

[0022] The drawings constituting a part of the specification of the application are used to provide further understanding of the application, the illustrative embodiments of the application and the description thereof are used to explain the application, and do not constitute improper limitation on the application.

[0023] Figure 1 is the preparation process of the Ni-doped Co3O4@C aqueous hybrid supercapacitor electrode material prepared in embodiment 1 of the application;

[0024] Figure 2 is the SEM scanning electron microscope image of the Ni-doped Co3O4@C prepared in embodiment 1;

[0025] Figure 3 is the XRD image of the Ni-doped Co3O4@C prepared in embodiment 1;

[0026] Figure 4 is the process diagram of the buckle type aqueous hybrid supercapacitor prepared in embodiment 3 of the application;

[0027] Figure 5 is the specific capacitance diagram of the buckle type aqueous hybrid supercapacitor prepared in embodiment 3 of the application under different current densities;

[0028] Figure 6 is the specific capacitance diagram of the buckle type aqueous hybrid supercapacitor prepared in embodiment 3 of the application under different current densities;

[0029] Figure 7 is the energy density diagram of the buckle type aqueous hybrid supercapacitor prepared in embodiment 3 of the application under different current densities;

[0030] Figure 8 is the power density diagram of the buckle type aqueous hybrid supercapacitor prepared in embodiment 3 of the application under different current densities;

[0031] Figure 9 is the cycle stability diagram of the buckle type aqueous hybrid supercapacitor prepared in embodiment 3 of the application. DETAILED DESCRIPTION

[0032] It should be noted that the following detailed description is illustrative only and is intended to provide further description of the application; unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0033] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present application; as used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise, it will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, steps, operations, elements, components, and / or groups thereof, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups thereof.

[0034] In particular, the present application is realized by the technical solutions as described below:

[0035] The first typical embodiment of the present application provides a preparation method of a Ni-doped Co3O4@C aqueous system hybrid supercapacitor electrode material, the method comprising:

[0036] S1. Dissolve NH4Cl into ammonia water, then add finely ground CoCl2 and finely ground NiCl2 in batches, continuously stir with a glass rod during the dissolution process to obtain a yellow-red turbid solution;

[0037] S2. Under stirring, add H2O2 solution dropwise to the above yellow-red turbid solution, and after the addition is completed, a purple-red solution is obtained;

[0038] S3. Under stirring, add concentrated hydrochloric acid dropwise to the above purple-red solution, and after the addition is completed, a purple-red precipitate is precipitated;

[0039] S4. Add activated carbon to the mixed solution in which the purple-red precipitate is precipitated, heat in a steam bath for a period of time, then cool to room temperature, perform suction filtration, wash and dry to obtain a dark purple solid;

[0040] S5. Place the dark purple solid in a muffle furnace for calcination to obtain a black powder-like solid Ni-doped Co3O4@C.

[0041] In one or more embodiments, the mass ratio of the three of NH4Cl, CoCl2 and NiCl2 is 1:1~1.1:1~1.1, preferably 1:1.025:1.025.

[0042] In one or more embodiments, the concentration of the ammonia water is 25%~28%, preferably 25%.

[0043] In one or more embodiments, the mass ratio of the ammonia water to NH4Cl is 1:1.3~1.4, preferably 1:1.365.

[0044] In one or more embodiments, the concentration (mass fraction of solute) of the H2O2 solution is 25~35%, preferably 30%.

[0045] In one or more embodiments, the mass ratio of the H2O2 solution to NH4Cl is 1.5~1.7:1, preferably 1.6:1.

[0046] In one or more embodiments, the concentration of the concentrated hydrochloric acid is 36~38%, preferably 37%.

[0047] In one or more embodiments, the mass ratio of the concentrated hydrochloric acid to NH4Cl is 7~8:1, preferably 7.735:1.

[0048] In one or more embodiments, the mass ratio of the activated carbon to NH4Cl is 0.4~0.8:1, preferably 0.5:1.

[0049] In one or more embodiments, the temperature of the steam bath is 100℃; the heating time of the steam bath is 25~35min, preferably 30min.

[0050] In one or more embodiments, the conditions of the washing are: washing with cold water for 3~5 times, washing with a hydrochloric acid solution once, washing with ethanol once, and washing with acetone once.

[0051] Preferably, the concentration (mass fraction of solute) of the hydrochloric acid solution is 19~21%, preferably 20%.

[0052] In one or more embodiments, the calcination conditions are: calcination at 450~550℃ for 50~70min, preferably calcination at 500℃ for 60min.

[0053] The second typical embodiment of the present application provides a Ni-doped Co3O4@C-based aqueous hybrid supercapacitor electrode material prepared by the above preparation method.

[0054] The third typical embodiment of the present application provides application of the above Ni-doped Co3O4@C-based aqueous hybrid supercapacitor electrode material in preparation of a supercapacitor.

[0055] The fourth typical embodiment of the present application provides a preparation method of a positive electrode sheet and a negative electrode sheet in an aqueous hybrid supercapacitor, which comprises:

[0056] Preparation of the positive electrode sheet: Ni-doped Co3O4@C, acetylene black, polyvinylidene fluoride and N-methyl-2-pyrrolidone (NMP) are respectively poured into a mortar for grinding, and the grinding is performed until the slurry is obtained and no fine particles are present; the ground slurry is uniformly coated on the foamed nickel, and the upper surface of the foamed nickel is ensured to be completely covered by the slurry, which is not transparent under sunlight; the coated foamed nickel is dried, and the positive electrode sheet of the button-type aqueous hybrid supercapacitor is obtained after drying.

[0057] Preparation of the negative electrode sheet: active carbon, acetylene black, polyvinylidene fluoride and N-methyl-2-pyrrolidone (NMP) are respectively poured into a mortar for grinding, and the grinding is performed until the slurry is obtained and no fine particles are present; the ground slurry is uniformly coated on the foamed nickel, and the upper surface of the foamed nickel is ensured to be completely covered by the slurry, which is not transparent under sunlight; the coated foamed nickel is dried, and the negative electrode sheet of the button-type aqueous hybrid supercapacitor is obtained after drying.

[0058] In the preparation process of the positive electrode sheet and the negative electrode sheet, the acetylene black acts as a conductive agent, the polyvinylidene fluoride acts as a binder, and the N-methyl-2-pyrrolidone (NMP) acts as a solvent for dissolving the binder polyvinylidene fluoride.

[0059] In one or more embodiments, in the preparation of the positive electrode sheet, the mass ratio of Ni-doped Co3O4@C, acetylene black, polyvinylidene fluoride and N-methyl-2-pyrrolidone is 70-80:10-20:8-12:280-320, and preferably 75:15:10:300.

[0060] In one or more embodiments, in the preparation of the negative electrode sheet, the mass ratio of active carbon, acetylene black, polyvinylidene fluoride and N-methyl-2-pyrrolidone is 70-80:10-20:8-12:280-320, and preferably 75:15:10:300.

[0061] In one or more embodiments, the foamed nickel in the positive electrode sheet and the negative electrode sheet is the same, and the foamed nickel is a foamed nickel sheet with a diameter of Φ=11-13 mm, and preferably a diameter of Φ=12 mm.

[0062] In one or more embodiments, the drying conditions of the positive electrode sheet and the negative electrode sheet are the same, and the drying conditions are as follows: the foamed nickel is placed in an oven and dried at a temperature of 100-130℃ for 0.5-1.5h, and preferably dried at a temperature of 120℃ for 1h.

[0063] In a fifth typical embodiment of the present application, the positive electrode sheet and the negative electrode sheet of the aqueous hybrid supercapacitor prepared by the above preparation method are provided.

[0064] In a sixth typical embodiment of the present application, a button-type water-based hybrid supercapacitor is provided, which comprises a positive electrode shell, a positive electrode sheet of the water-based hybrid supercapacitor, a separator, a negative electrode sheet of the water-based hybrid supercapacitor, a negative electrode shell, and an electrolyte solution; and the electrolyte solution is a KOH solution.

[0065] In one or more embodiments, the positive electrode shell is made of stainless steel, and has a diameter of 18-22 mm, preferably 20 mm.

[0066] In one or more embodiments, the negative electrode shell is made of stainless steel, and has a diameter of 18-22 mm, preferably 20 mm.

[0067] In one or more embodiments, the separator is made of P.P. polypropylene.

[0068] In one or more embodiments, the separator has a diameter of 15-17 mm, preferably 16 mm.

[0069] In one or more embodiments, the KOH solution has a concentration of 1-3 mol / L, preferably 2 mol / L.

[0070] In one or more embodiments, the button-type water-based hybrid supercapacitor is prepared by the following method:

[0071] Treatment of the electrode sheets: a drop of the electrolyte KOH solution is added to each of the positive electrode sheet and the negative electrode sheet, and the KOH solution is allowed to soak into the electrode sheets;

[0072] Fixing of the electrode sheets: a drop of the electrolyte KOH solution is added to the center of each of the positive electrode shell and the negative electrode shell, and the treated positive electrode sheet and the treated negative electrode sheet are placed in the center of the positive electrode shell and the negative electrode shell, respectively, so that the positive electrode sheet and the negative electrode sheet are fixed to the positive electrode shell and the negative electrode shell by means of the surface tension of the liquid;

[0073] Assembly: the separator is placed directly above the positive electrode sheet, a drop of the electrolyte KOH solution is added to the positive electrode shell, so that the electrolyte fills the entire positive electrode shell, and the negative electrode shell with the negative electrode is inverted and placed directly above the positive electrode shell, so that the entire device is tightly sealed and no liquid leakage occurs; the entire device is packaged using an electric button cell sealing press, thereby obtaining the button-type water-based hybrid supercapacitor.

[0074] In order to enable those skilled in the art to more clearly understand the technical solutions of the present application, the technical solutions of the present application will be described in detail below with reference to specific embodiments.

[0075] Embodiment 1

[0076] According to Figure 1The preparation process shown prepared Ni-doped Co3O4@C

[0077] Dissolve 2.0 g of NH4Cl into 12 mL of ammonia water with a concentration of 25%, then add 2.05 g of finely ground CoCl2 and 2.05 g of finely ground NiCl2 in batches, and constantly stir with a glass rod to form a yellow-red turbid solution. Under stirring, add 3.2 mL of 30% H2O2 solution dropwise to the above yellow-red turbid solution, and after the dropwise addition is completed, a purple-red solution is obtained. Under stirring, add 13 mL of 37% concentrated hydrochloric acid dropwise to the above purple-red solution, and after the dropwise addition is completed, a purple-red precipitate is precipitated. Add 1 g of activated carbon to the above mixture in which the purple-red precipitate is precipitated, heat in a steam bath at 100°C for 30 min, cool to room temperature, and perform suction filtration. The precipitate after suction filtration is washed with 10 mL of cold water for 3-5 times, then washed with 6 mL of 20% hydrochloric acid solution, then washed with 3 mL of ethanol, and finally washed with 3 mL of acetone; after air drying, a dark purple solid is obtained. Place the dark purple solid on a glass plate and heat in a muffle furnace, first increase to 500°C for one and a half hours, then maintain for one hour, and finally decrease to room temperature for one and a half hours, to obtain black powdery solid Ni-doped Co3O4@C.

[0078] The Ni-doped Co3O4@C prepared in Example 1 was characterized, Figure 2 The SEM electron scanning image is as shown in Figure 2 The Ni-doped Co3O4@C prepared in this embodiment has a tetragonal bipyramidal structure, and the exposed 111 plane of this special structure is the most stable, which can improve the stability of the capacitor.

[0079] Figure 3 The XRD image is as shown in Figure 2 The Ni-doped Co3O4@C prepared in this embodiment corresponds completely to the simulation image, indicating that the Ni-doped Co3O4@C prepared in this embodiment has high purity and does not contain other impurities.

[0080] Example 2

[0081] Preparation of positive and negative electrode sheets in aqueous hybrid supercapacitors

[0082] The Ni-doped Co3O4@C, acetylene black, polyvinylidene fluoride, N-methyl-2-pyrrolidone (NMP) are added into a mortar in a mass ratio of 75:15:10:300, and are ground into a slurry state and without fine particles by using a hammer; a Φ =12 mm nickel foam is taken, the nickel foam is adhered to the reverse side of a culture dish by using double-sided tape, the prepared slurry is uniformly coated on the nickel foam by using the hammer in the mortar, the slurry is coated on the edge position by using a medicine spoon, and it is ensured that the upper surface of the nickel foam is completely covered by the slurry and is not transparent under sunlight; after uniform coating, the nickel foam coated with the active material is placed into an oven, and is dried at 120℃ for 1h, and the positive electrode sheet for the button-type aqueous hybrid supercapacitor is obtained after drying.

[0083] The activated carbon acetylene black, polyvinylidene fluoride, N-methyl-2-pyrrolidone (NMP) are added into a mortar in a mass ratio of 75:15:10:300, and are ground into a slurry state and without fine particles by using a hammer; a Φ =12 mm nickel foam is taken, the nickel foam is adhered to the reverse side of a culture dish by using double-sided tape, the prepared slurry is uniformly coated on the nickel foam by using the hammer in the mortar, the slurry is coated on the edge position by using a medicine spoon, and it is ensured that the upper surface of the nickel foam is completely covered by the slurry and is not transparent under sunlight; after uniform coating, the nickel foam coated with the active material is placed into an oven, and is dried at 120℃ for 1h, and the negative electrode sheet for the button-type aqueous hybrid supercapacitor is obtained after drying.

[0084] Example 3

[0085] The button-type aqueous hybrid supercapacitor is prepared according to the preparation process as shown in Figure 4

[0086] (1) Treatment of the electrode: one drop of 2mol / L KOH solution is dropped on the positive electrode sheet and the negative electrode sheet respectively, and the electrode sheet is immersed in the KOH solution.

[0087] (2) Fixing of the electrode sheet: one drop of 2mol / L KOH solution is dropped on the center of the Φ =20 mm positive electrode shell and the Φ =20 mm negative electrode shell respectively, and the treated positive electrode sheet and the negative electrode sheet are respectively placed in the center of the positive electrode shell and the negative electrode shell, and the positive electrode sheet and the negative electrode sheet are fixed on the positive electrode shell and the negative electrode shell by means of the surface tension of the liquid.

[0088] ​(3) Put the Φ = 16 mm diaphragm on the positive electrode sheet, drop the electrolyte KOH solution into the positive electrode shell, so that the electrolyte fills the entire positive electrode shell, and transfer the entire positive electrode shell to the electric button cell sealing press machine. The negative electrode shell is inverted on the positive electrode shell, and the position of the negative electrode shell can be adjusted so that the negative electrode shell is just above the positive electrode shell, and the entire device is tightly sealed and no liquid leakage occurs. Adjust the pressure of the electric button cell sealing press machine to 0.9T, press the start key, and the button cell is sealed by the sealing machine. Finally, use degreasing cotton soaked with alcohol to wipe the overflowed electrolyte solution during the sealing process to prevent the solution from corroding the instrument, and the button cell water-based hybrid supercapacitor is obtained.

[0089] The button cell water-based hybrid supercapacitor prepared in this embodiment was characterized:

[0090] As shown in Figure 5 , under the same current density, the specific capacitance of the supercapacitor with Ni-doped Co3O4@C as the positive electrode material was significantly higher than that of the supercapacitors prepared with the other two materials (Co3O4, Ni-doped Co3O4). The specific capacitance of the three supercapacitors decreased with increasing current density, and the specific capacitance of the supercapacitor with Ni-doped Co3O4@C as the positive electrode material decreased by 45%, which was lower than the specific capacitance decrease rate of the supercapacitors prepared with the other two materials (Co3O4: 51.4%, Ni-doped Co3O4: 55.2%). Therefore, the supercapacitor with Ni-doped Co3O4@C as the positive electrode material has good electrochemical performance.

[0091] As shown in Figure 6 , the specific capacitance of the button cell water-based hybrid supercapacitor prepared in this embodiment was measured at different current densities, and it was found that the specific capacitance gradually decreased with increasing current density, from 79.62 mF·cm -2 to 44.23 mF·cm -2 .

[0092] As shown in Figure 7 , the energy density of the button cell water-based hybrid supercapacitor prepared in this embodiment was measured at different current densities, and it was found that the energy density gradually decreased with increasing current density, from 0.23 Wh·kg -1 to 0.13 Wh·kg -1 .

[0093] As shown in Figure 8As shown in the figure, the power density of the button-shaped water-based hybrid supercapacitor prepared in the embodiment is measured at different current densities, and it is found that as the current density increases, the power density decreases from 5.75 W·kg -1 to 114.94 W·kg -1 .

[0094] As Figure 9 shown, the button-shaped water-based hybrid supercapacitor prepared in the embodiment is subjected to cycle stability detection at a current density of 0.88 mA·cm -2 The specific capacitance of the first cycle is 58.61 mF·cm -2 , the energy density is 0.17 Wh·kg -1 , the power density is 11.49 W·kg -1 , the specific capacitance of the first ten thousand cycles is 49.76 mF·cm -2 , the energy density is 0.14 Wh·kg -1 , and the power density is 14.58 W·kg -1 . It is shown that the button-shaped water-based hybrid supercapacitor prepared in the embodiment has excellent cycle stability.

[0095] The above only describes the preferred embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing an electrode material for a Ni-doped Co3O4@C aqueous hybrid supercapacitor, characterized in that, The method includes: NH4Cl was dissolved in ammonia water, and then finely ground CoCl2 and finely ground NiCl2 were added in batches. During the dissolution process, the mixture was stirred continuously with a glass rod to obtain a yellow-red turbid solution. The mass ratio of NH4Cl, CoCl2 and NiCl2 was 1:1~1.1:1~1.

1. While stirring, add H2O2 solution dropwise to the above yellow-red turbid solution. After the addition is complete, a purple-red solution is obtained. While stirring, add concentrated hydrochloric acid (36-38%) dropwise to the above purple-red solution. After the addition is complete, a purple-red precipitate will form. Activated carbon was added to the mixture in which a purple-red precipitate was formed. After heating in a steam bath for a period of time, the mixture was cooled to room temperature, filtered, washed, and dried to obtain a dark purple solid. The mass ratio of activated carbon to NH4Cl was 0.4~0.8:

1. The dark purple solid was placed in a muffle furnace for calcination to obtain a black powdery solid Ni-doped Co3O4@C. The calcination conditions were: calcination at 450~550℃ for 50~70 min. The Ni-doped Co3O4@C is a novel material with a tetragonal bipyramidal structure formed by calcining cobalt complexes doped with carbon and nickel.

2. The preparation method according to claim 1, characterized in that, The concentration of the ammonia water is 25%~28%; Alternatively, the mass ratio of the ammonia water to NH4Cl is 1:1.3~1.4; Alternatively, the mass fraction of the H2O2 solution is 25-35%; Alternatively, the mass ratio of the H2O2 solution to NH4Cl is 1.5~1.7:1; Alternatively, the mass ratio of the concentrated hydrochloric acid to NH4Cl is 7~8:1; Alternatively, the temperature of the steam bath is 100°C; the heating time of the steam bath is 25~35 minutes. Alternatively, the washing conditions are as follows: first wash with cold water 3 to 5 times, then wash with hydrochloric acid solution once, then wash with ethanol once, and finally wash with acetone once; the concentration of the hydrochloric acid solution is 19 to 21%.

3. The preparation method according to claim 1, characterized in that, The mass ratio of NH4Cl, CoCl2, and NiCl2 is 1:1.025:1.

025.

4. The preparation method according to claim 1, characterized in that, The concentration of the concentrated hydrochloric acid is 37%.

5. The preparation method according to claim 1, characterized in that, The mass ratio of activated carbon to NH4Cl is 0.5:

1.

6. The preparation method according to claim 1, characterized in that, The calcination conditions are: calcination at 500℃ for 60 minutes.

7. The preparation method according to claim 2, characterized in that, The concentration of the ammonia water is 25%.

8. The preparation method according to claim 2, characterized in that, The mass ratio of ammonia to NH4Cl is 1:1.

365.

9. The preparation method according to claim 2, characterized in that... The H2O2 solution has a mass fraction of 30%.

10. The preparation method according to claim 2, characterized in that, The mass ratio of the H2O2 solution to NH4Cl is 1.6:

1.

11. The preparation method according to claim 2, characterized in that, The mass ratio of concentrated hydrochloric acid to NH4Cl is 7.735:

1.

12. The preparation method according to claim 2, characterized in that, The heating time of the steam bath is 30 minutes.

13. The preparation method according to claim 2, characterized in that, The concentration of the hydrochloric acid solution used in the washing process is 20%.

14. The electrode material of a Ni-doped Co3O4@C aqueous hybrid supercapacitor prepared by the preparation method according to any one of claims 1 to 2.

15. The Ni-doped Co3O4@C aqueous hybrid supercapacitor electrode material of claim 14 is used in the preparation of supercapacitors.

16. A method for preparing the positive and negative electrode plates in an aqueous hybrid supercapacitor, characterized in that, The method includes: Preparation of the positive electrode: Ni-doped Co3O4@C, acetylene black, polyvinylidene fluoride, and N-methyl-2-pyrrolidone prepared by the preparation method according to any one of claims 1 to 2 are respectively poured into a mortar and ground until a slurry is formed and free of fine particles; the ground slurry is uniformly coated onto nickel foam, ensuring that the entire surface of the nickel foam is covered by the slurry and is opaque under sunlight; the coated nickel foam is dried, and the positive electrode of the button-type aqueous hybrid supercapacitor is obtained after drying; Preparation of the negative electrode: Activated carbon, acetylene black, polyvinylidene fluoride and N-methyl-2-pyrrolidone are respectively poured into a mortar and ground until they are in slurry and free of fine particles; the ground slurry is evenly coated on nickel foam to ensure that the entire surface of the nickel foam is covered by the slurry and is opaque in sunlight; the coated nickel foam is dried, and the negative electrode of the button-type aqueous hybrid supercapacitor is obtained after drying.

17. The preparation method according to claim 16, characterized in that, In the preparation of the positive electrode, the mass ratio of Ni-dopedCo3O4@C, acetylene black, polyvinylidene fluoride, and N-methyl-2-pyrrolidone is 70~80:10~20:8~12:280~320. Alternatively, in the preparation of the negative electrode sheet, the mass ratio of activated carbon, acetylene black, polyvinylidene fluoride, and N-methyl-2-pyrrolidone is 70~80:10~20:8~12:280~320. Alternatively, the positive electrode and the negative electrode may contain the same nickel foam, wherein the nickel foam is a nickel foam sheet with a diameter of Φ=11~13mm; Alternatively, the positive electrode sheet and the negative electrode sheet are dried under the same conditions, namely: placed in an oven and dried at 100~130℃ for 0.5~1.5h.

18. The preparation method according to claim 16, characterized in that, In the preparation of the positive electrode, the mass ratio of Ni-dopedCo3O4@C, acetylene black, polyvinylidene fluoride, and N-methyl-2-pyrrolidone is 75:15:10:

300.

19. The preparation method according to claim 16, characterized in that, In the preparation of the negative electrode sheet, the mass ratio of activated carbon, acetylene black, polyvinylidene fluoride, and N-methyl-2-pyrrolidone is 75:15:10:

300.

20. The preparation method according to claim 16, characterized in that, The positive electrode and the negative electrode contain the same foamed nickel, which is a foamed nickel sheet with a diameter of 12 mm.

21. The preparation method according to claim 16, characterized in that, The positive electrode and the negative electrode are dried under the same conditions, namely, drying at 120°C for 1 hour.

22. The positive and negative electrode plates in the aqueous hybrid supercapacitor prepared by the preparation method according to any one of claims 16-17.

23. A button-type aqueous hybrid supercapacitor, characterized in that, The button-type aqueous hybrid supercapacitor comprises a positive electrode shell, a positive electrode sheet and a separator as described in claim 16, a negative electrode sheet and a negative electrode shell as described in claim 16, and an electrolyte; the electrolyte is a KOH solution.

24. The button-type aqueous hybrid supercapacitor as described in claim 23, characterized in that, The positive electrode shell is made of stainless steel and has a diameter of 18~22mm; Alternatively, the negative electrode shell is made of stainless steel and has a diameter of 18~22mm; Alternatively, the membrane may be composed of PP (polypropylene). Alternatively, the diaphragm Φ = 15~17 mm; Alternatively, the concentration of the KOH solution is 1~3 mol / L.

25. The button-type aqueous hybrid supercapacitor as described in claim 23, characterized in that, The positive electrode shell is made of stainless steel and has a diameter of 20mm.

26. The button-type aqueous hybrid supercapacitor as described in claim 23, characterized in that, The negative electrode shell is made of stainless steel and has a diameter of 20mm.

27. The button-type aqueous hybrid supercapacitor as described in claim 23, characterized in that, The diaphragm has a diameter of Φ=16mm.

28. The button-type aqueous hybrid supercapacitor as described in claim 23, characterized in that, The concentration of the KOH solution is 2 mol / L.

29. The button-type aqueous hybrid supercapacitor as described in claim 23, characterized in that, The method for preparing the button-type aqueous hybrid supercapacitor is as follows: Electrode preparation: Add a drop of KOH solution to the positive electrode and the negative electrode respectively, and wait for the KOH solution to immerse the electrode. Fixing the electrode plates: Drop a drop of KOH electrolyte solution into the center of the positive electrode shell and the negative electrode shell respectively. Place the treated positive electrode plate and negative electrode plate in the center of the positive electrode shell and the negative electrode shell respectively. The positive electrode plate and the negative electrode plate will be fixed on the positive electrode shell and the negative electrode shell by means of the surface tension of the liquid. Assembly: Place the separator directly above the positive electrode, and drip KOH solution into the positive electrode shell to fill the entire positive electrode shell with electrolyte. Invert the negative electrode shell with the negative electrode directly above the positive electrode shell to ensure that the entire device is tightly sealed and there is no leakage. Use an electric button cell sealing and pressing machine to seal the entire device to obtain the button-type aqueous hybrid supercapacitor.

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